For many years, chemical solutions have been stored and mixed in sterilizable containers. These containers typically include stopper or screw-on closures which are held in the hand of the user (together with the container) to cut-down on contamination of the solution which would otherwise occur if the closure were to be placed on an unsterile surface. Although these closures have become quite common, they are often difficult to hold by those having relatively small hands and/or they require sterilization after each use.
Typical stopper closures (such as pennyhead stoppers available from Aldrich Chemical Company, Inc., product numbers Z10, Z11 or Z17) may be easily removed from a container and held between the fingers of a user. However, because the stopper portion of the closure is exposed to the air and later returned to the interior of the container, the stopper must be sterilized after each use to avoid contaminating the solution with bacteria which may have come into contact with the stopper portion of the closure. Moreover, stopper closures do not ensure absolute sealing of the container, as a stopper closure may become dislodged if the container were accidentally knocked over.
On the other hand, screw-on closures, which do not come into contact with the interior of a container, are screwed about the neck portion of a container to close the same. In order to avoid contamination of the closure (by placing the closure on an unsterile surface, for example), the user often holds the closure within the palm of the hand which is also holding the container. It may not be feasible to hold the closure in the other free hand, as the other hand is often needed for pipetting or to hold other containers. If the neck portion of the container is relatively large (which it usually is to allow introduction of instruments into the container), the closure is also large and therefore difficult to hold by those having relatively small hands. Thus, while it is desirable to provide a container with a large opening, it is undesirable to have a large closure therefor.
In an effort to solve this problem, large-orifice, flip-top closures have been developed. An example of such a closure is the 38-400 CC-2 manufactured by Sunbeam Plastics Corp., Evansville, Ind. The closure is a two-piece unit comprised of a threaded base and a hinged flip top. When the user wishes to pour the contents from the container, the flip top is simply opened and the contents of the container are poured therefrom. The closure unit is never removed from the container; thus, the closure is never held within the hand of the user and the risk of contamination is decreased. However, when a liquid is poured from the flip-top dispenser, the flow path of the liquid is interrupted and liquid spills down the outer surface of the closure and container. This spilled liquid may become contaminated with airborne bacteria and thereby contaminate the solution within the container. Therefore, to decrease contamination risks, the flip-top closure and the container must be sterilized after each use. Moreover, the internal structure of the flip-top may interfere with the introduction of instruments into the container. When inserting a pipette (for example) into a container, it is imperative that the pipette not touch any interior surface of the container or closure. Finally, manufacture of a two-piece, flip-top closure is relatively difficult.
Other flip-top closures are disclosed in U.S. Pat. Nos. 2,950,833, 4,881,668 and 5,085,331. The orifices of these closures, however, are relatively small and would obstruct or interfere with the introduction of instruments into the container.
Therefore, it is an object of the present invention to provide a closure for a container which does not obstruct the opening of the container.
Another object of the invention is to provide a closure for a container which may be easily held within the user's hand.
A further object of the invention is to provide a closure for a container which may be easily removed from the container.
Yet another object of the invention is to provide a closure for a container which does not interfere with storage or shelving of the container.
Still another object of the invention is to provide a closure for a container which is easily manufactured and sterilizable.